Washington (CNN) -- Michelle Obama expressed confidence Tuesday that Congress will enact some sort of change to improve the nation's health care system.
"We don't have a choice," the first lady told CNN's Larry King in an interview that aired Tuesday night. "When we look at these statistics, we're spending billions of dollars on preventable diseases, and new health care legislation could go a long way to improving prevention, first and foremost."
She addressed the need for people to have access to specialists such as pediatricians who can gather critical information and track it.
"So we have to get this done and I'm hopeful that Congress will come together, that the American people will recognize that doing nothing is absolutely not an option."
Obama's appearance coincided with the launch of her initiative to improve the fitness of young people, starting with her own two grade-school children. Obama said her daughters, Sasha and Malia, were not eating right and not exercising enough before her husband won the White House, and it showed in their body-mass index.
"I was fortunate enough to have a pediatrician who worked in an urban environment in the African-American community," she said. And he was tracking BMI. And he saw little uptick in the kids' BMI, and he kind of pulled me aside."
Obama said she was initially shocked.
"I thought I was doing what I was supposed to do, and I hadn't noticed any changes in my kids," she said. But she accepted the doctor's admonition as a "wake-up call" and began to make changes.
"It was portion sizes; it was a few more cooked meals," she said. "We had no absolutes except no desserts during the week. Took sugary drinks out of the lunch boxes and put in water and had more milk, had more fresh-squeezed juices, things like that."
The 44-year-old Chicagoan said she felt it was important to share her family's success with other Americans and to point out that the changes they made were manageable ones.
"The point is that small changes made a difference," she said. "It wasn't a whole-scale upheaval of our lives to see the outcomes."
According to the Centers for Disease Control and Prevention, 12.4 percent of children ages 2 to 5 are obese; 17 percent of those 6 to 11 are obese; and 17.6 percent of those 12 to 19 are obese.
Obesity is linked to risk factors associated with cardiovascular disease, such as high blood pressure, high cholesterol and Type 2 diabetes.
"This isn't about weight, and it's not about looks," Obama said. "It's not a physical issue. It's really about the quality of life of our kids."
Though members of the first family eat less fast food than they once did, they have not eliminated it from their diets, the first lady said.
"What I tell my kids is if they're eating right, you know, 70 percent of the time, then when they go to a birthday party or it's a Saturday and they're out and they can stop for ice cream and somebody wants to grab pizza, or they have pancakes with chocolate chips in it, it's not a big deal."
The graduate of Princeton University and Harvard Law School said she works to keep the White House "sort of a stress-free, work-free zone" for her husband.
In some ways, the family's life is like many others', she said. Her husband reads to the children at night and tucks them into bed.
"He still goes to the parent-teacher conferences. ... He goes to basketball games and soccer games. He can't go to every single one of them because some -- on Saturdays, oftentimes, he's working."
Still, the trappings of power can be limiting. He does not drop his children off at the nearby Sidwell Friends School.
"Quite frankly, they don't want him to," she said. "They think his motorcade is a complete embarrassment."
The first lady described life in the White House as "like living in a big hotel with a whole bunch of fun people that you can work with. But then when -- when the doors close, it's -- it's like home."
She acknowledged, in response to a question, that sometimes her husband gets mad.
"Oh, yes. Yes, he's human. You know, if you prick him, he'll bleed."
But the president tries to maintain a constructive approach, she said. "He's always about finding the solution. And he knows if you go too far emotionally, if you get too angry or you -- if you become too complacent, sometimes you miss the answer in between. And that's, I think, one of the strengths of him as a leader."
Asked for her read on Sarah Palin, the former governor of Alaska who ran on the GOP ticket for vice president, Obama would not bite.
"I don't have a read," she said. "I mean, I try not to make or set opinions about people that I haven't had any, you know, substantive interaction with. I mean, I know what you see on TV."
She added, "I think it's wonderful to have strong female voices out there, but I don't know her."
The first lady was effusive about her husband's former rival for the top spot on the Democratic ticket, Hillary Clinton.
"She would have been an amazing president. She was an amazing attorney. She's a phenomenal professional. And she's proven to be a tremendous asset in -- in so many ways," she said.
Asked what she expects on Valentine's Day, Obama told King, "Oh, I expect the moon, the stars and the sun, honey."
Asked what she usually gets, she said, "I usually get dinner, and a gift of some sort."
And what does her husband get?
"A nice card."